The petroleum industry is increasingly turning to heavy crudes, resids, coals and tar sands, i.e., lower grade hydrocarbon (“heavy oil”), as sources for feedstocks. The upgrading or refining of these feedstocks is accomplished by treating the feedstocks with hydrogen in the presence of catalysts to effect conversion of at least a portion of the feeds to lower molecular weight hydrocarbons, or to effect the removal of unwanted components, or compounds, or their conversion to innocuous or less undesirable compounds.
In the hydroconversion process, catalysts that are unstabilized, or of limited mechanical integrity, undergo considerable shrinkage of their geometric volume when exposed to severe conditions. When the catalysts are used to fill a reactor space as in a fixed bed, the catalyst shrinkage produces unoccupied channels through which reactants can pass without being in contact with the catalyst. Channeling of reactants decreases effectiveness of the catalyst bed regardless of the activity of the catalyst in the reactor space. Catalyst shrinkage further decreases effectiveness of the bed utilization as less reactor volume is used. Lastly, the pressure drop across the reactor due to the catalyst's volumetric shrinkage can have a significant impact on the reactor performance.
There is still the need for a bulk/unsupported catalyst for use in the hydroconversion of lower grade hydrocarbon with improved performance, i.e., providing high yield conversions as well as exhibiting low shrinkage when exposed to high reaction temperatures.